LXTow
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How LLMs work

Understand how language models work by building one, step by step.

Start free

Free during early access · pricing

What you’ll learn

  • Tokenize text, embed words and watch attention pick what matters
  • Train a small GPT and see its loss fall, checkpoint by checkpoint
  • Fine-tune it to follow instructions, then teach it your taste with DPO
  • Chat with the model you built and read every token it chose

For example: Build a tokenizer by merging letters, one pair at a time.

Levels

ExplorerYou know the core ideas and can explain them.
BuilderYou’ve done every practice step and built the thing.
ArchitectYou’ve passed the final exam.